Abstract

A series of novel small molecule PHPD, TPAPD, and CZPD were designed and synthesized for probing their potential applications in photovoltaic devices. Differential scanning calorimetry (DSC) measurement reveals that PHPD displays amorphous property, while both TPAPD and CZPD exhibit crystalline properties. Ultraviolet–Visible (UV–Vis) absorption spectra demonstrate that these small molecules possess relatively broad absorption with absorption edges of 706 nm (PHPD), 671 nm (TPAPD), and 632 nm (CZPD), respectively. Cyclic voltammetry (CV) investigation indicates that the highest occupied molecular orbital (HOMO) energy levels were well tuned (−4.97, −5.24, and −5.38 eV) with the introduction of different electron-donating moieties. The device based on CZPD without further optimization displays the highest power conversion efficiency (PCE) of 2.00 % among three small molecules (1.21 % for TPAPD and 0.28 % for PHPD), which stands out as one of the highest values for photovoltaic devices based on 3-carbazole (CZ) derivatives. This result would uncover the potential applications of 3-carbazole-based donor materials for organic solar cells.

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Acknowledgement

This work was supported by the Research Program of 973 Program (No2014CB643506), the Research Program of Hubei Province Department of Education (T201215), Natural Science Foundation of Hubei Province (2012FFC05401), Foundation of Hubei Educational Committee (Q20122512, Q20122505), Open Foundation of Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices (13XKL02015).